/*
 * Copyright (C) 2007 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.collect;

import com.google.common.annotations.GwtCompatible;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import javax.annotation.Nullable;

/**
 * A {@code Multimap} that can hold duplicate key-value pairs and that maintains the insertion
 * ordering of values for a given key. See the {@link Multimap} documentation for information common
 * to all multimaps.
 *
 * <p>
 * The {@link #get}, {@link #removeAll}, and {@link #replaceValues} methods each return a
 * {@link List} of values. Though the method signature doesn't say so explicitly, the map returned
 * by {@link #asMap} has {@code List} values.
 *
 * <p>
 * See the Guava User Guide article on
 * <a href= "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap">
 * {@code Multimap}</a>.
 *
 * @author Jared Levy
 * @since 2.0
 */
@GwtCompatible
public interface ListMultimap<K, V> extends Multimap<K, V> {
    /**
     * {@inheritDoc}
     *
     * <p>
     * Because the values for a given key may have duplicates and follow the insertion ordering,
     * this method returns a {@link List}, instead of the {@link java.util.Collection} specified in
     * the {@link Multimap} interface.
     */
    @Override
    List<V> get(@Nullable K key);

    /**
     * {@inheritDoc}
     *
     * <p>
     * Because the values for a given key may have duplicates and follow the insertion ordering,
     * this method returns a {@link List}, instead of the {@link java.util.Collection} specified in
     * the {@link Multimap} interface.
     */
    @CanIgnoreReturnValue
    @Override
    List<V> removeAll(@Nullable Object key);

    /**
     * {@inheritDoc}
     *
     * <p>
     * Because the values for a given key may have duplicates and follow the insertion ordering,
     * this method returns a {@link List}, instead of the {@link java.util.Collection} specified in
     * the {@link Multimap} interface.
     */
    @CanIgnoreReturnValue
    @Override
    List<V> replaceValues(K key, Iterable<? extends V> values);

    /**
     * {@inheritDoc}
     *
     * <p>
     * <b>Note:</b> The returned map's values are guaranteed to be of type {@link List}. To obtain
     * this map with the more specific generic type {@code Map<K, List<V>>}, call
     * {@link Multimaps#asMap(ListMultimap)} instead.
     */
    @Override
    Map<K, Collection<V>> asMap();

    /**
     * Compares the specified object to this multimap for equality.
     *
     * <p>
     * Two {@code ListMultimap} instances are equal if, for each key, they contain the same values
     * in the same order. If the value orderings disagree, the multimaps will not be considered
     * equal.
     *
     * <p>
     * An empty {@code ListMultimap} is equal to any other empty {@code
     * Multimap}, including an empty {@code SetMultimap}.
     */
    @Override
    boolean equals(@Nullable Object obj);
}
